Until recently digital processing of biomedical images was conducted solely in the research laboratories of the universities and industry. However, with the advent of computerized tomography in 1972 and the computerized white blood cell differential count in 1974, enormous changes have suddenly occurred. Digital image pro­ cessing in biomedicine has now become the most active sector in the digital image processing field. Processing rates have reached the level of one trillion picture elements per year in the United States alone and are expected to be ten trillion per year in 1980. This enormous volume of activity has stimulated further re­ search in biomedical image processing in the last two years with the result that important inroads have been made in applications in radiology, oncology, and ophthalmology. Although much significant work in this field is taking place in Europe, it is in the United States and Japan that the level of activity is highest.